DE. A. DUPEE ON THE SPECIFIC HEAT AND OT1IEE 
rotated under water. This vessel, when filled, is heated in a Fegnault’s steam-oven by 
the vapour of methylic alcohol ; and when the temperature has become constant it is 
lowered into the calorimeter, hooked on to a wire, and made to spin round underneath 
the surface of the water ; a second observer meanwhile watches the thermometer of the 
calorimeter. The temperature of this rises, rapidly at first, more slowly towards the 
end, and reaches a maximum in from two to three minutes. The thermometer is 
observed during the next succeeding 1 to 1^ minute, and the fall observed is added as 
a correction to the highest temperature reached. The results obtained are not quite as 
concordant as those yielded by the method chiefly employed in estimating the specific 
heat of mixtures of ethylic alcohol and water (Philosophical Transactions, 1869, p. 591), 
owing principally to the difficulty of keeping the temperature of the steam-oven con- 
stant for a sufficient length of time when the vapour of methylic alcohol, instead of 
steam, is used for heating. Methylic alcohol has, however, too low a boiling-point for 
the successful application of the former method. 
From the data obtained the specific heat of the mixture is calculated by help of the 
following formula : — 
_C__ W ^ 
100 m (T — t 1 ) m 
wherein C is the specific heat sought, 
W the water value of calorimeter and contents (water, thermometer, and calorimeter 
itself), 
t temperature of calorimeter at the beginning, 
t" temperature of calorimeter at end, correction added, 
T temperature of steam-oven, 
m weight of mixture employed, 
[jj water value of annular brass vessel, 
t' temperature of calorimeter at end, without correction. 
In the following Table the experiments marked with an asterisk were made with 
methylic alcohol of one preparation, those not so marked with spirit of another prepa- 
ration. 
Table I. 
Amount of water in calorimeter 115G-G6G grins. 
Water value of calorimeter 8-565 grms. 
Water value of annular brass vessel (p) was G'8337 grms. in all experiments with an 
asterisk, and G'6572 grms. in the others. 
Water value of immersed part of thermometer 1-139. 
Time occupied in each experiment, 3 to 4-| minutes. 
